Year	U.S. dollars (Units)
1980	793.112
1981	812.633
1982	782.719
1983	711.880
1984	691.194
1985	611.274
1986	529.419
1987	540.761
1988	598.335
1989	570.057
1990	689.000
1991	709.333
1992	815.246
1993	885.848
1994	1153.358
1995	1306.637
1996	1381.767
1997	1385.676
1998	1171.173
1999	1215.225
2000	1017.394
2001	965.938
2002	795.544
2003	788.629
2004	866.985
2005	1014.727
2006	1119.587
2007	1260.251
2008	1389.053
2009	1428.609
2010	1604.149
2011	1938.786
2012	2131.454
2013	2250.761
2014	2274.897
2015	2168.568
2016	2227.003
2017	2310.860
2018	2474.440
2019	2417.332
2020	2236.417
2021	2114.817
2022	2161.970
2023	2204.929
2024	2252.633
2025	2342.918
2026	2427.663
2027	2519.405
2028	2611.120
2029	2704.343